Hydraulic system for driving several actuators



P 1961 D. c. ALLAlS ET AL 3,001,369

HYDRAULIC SYSTEM FOR DRIVING SEVERAL ACTUATORS Filed Jan. 7, 1960 INVENTORS. DAVID C. ALLA\S NORMAN A. VOGEL BY%744% v ATTORNEY United States Patent 3,001,369 HYDRAULIC SYSTEM FOR DRIVING SEVERAL ACTUATORS David C. Allais and Norman Vogel, Saratoga, Califi, assignors to International Business Machines Corporation, New York, N .Y., a corporation of New York Filed Jan. 7, 1960, Ser. No. 1,052 4 Claims. (Cl. 6054.5)

This invention relates to a fluid actuator system par.- ticularly applicable for displacing a selected one of a number of slave pistons each acting within an associated cylinder. More particularly, it relates to an improvement upon the complementary volume-added of co-pending application, Serial No. 779,582, entitled Positioning Device.

In the subject application, Serial No. 779,582, there is shown a hydraulic positioning device which includes a slave cylinder having a movable piston and a plurality of actuation cylinders arranged in pairs with one cylinder of each pair hydraulically connected to one end of the slave cylinder and the other cylinder of each pair hydraulically connected to-the other end of the slave cylinder. During each positioning operation, a mechanical drive means acting through clutches displaces the pistons of one or more selected pairs of actuation cylinders such that hydraulic fluid is forced into one end of the slave cylinder and extracted from the other end, thereby moving the piston. if positive displacement of fluid is. defined such that an actuation cylinder injects fluid into the slave cylinder, and negative displacement is defined such that fluid is extracted from the slave cylinder, then it may be concluded that the piston of the slave cylinder will be moved in accordance with the algebraic sum of all the displacements of those cylinders hydraulically connected to the input or pressure end of the slave cylinder. Since the selective drive means, or cams, acting through clutches is arranged to displace the actuation cylinders of each selected pair in an opposite or complementary sense, the fluid injected into one end of the slave cylinder is always equal to the fluid extracted from the other end thereof. The foregoing arrangement is sometimes referred to as a complementary volume-added since not only are volumes of fluid combined to displace a slave piston in accordance with their aggregate amount (as in a conventional volume adder) but each of the actuation cylinders simultaneously expels at one end and receives at the other end that amount of fluid which it contributes to the aggregate.

The prior device, as thus described, which employed clutches to select one or more actuating pistons to be moved, did not appear to be readily adaptable to the selective control of a number of slave pistons without providing means to reset all actuator pistons after each move. in other words, the maximum combined volumes of fluid, for example, would not be available during every stroke of the mechanical drive means, if, prior to any particular stroke, one or more of the actuator pistons which had previously been displaced had not been reset.

Briefly stated, in the present invention simple hydraulic valving has taken the place of the selector clutches of the prior device with the result that the need for reset means has been obviated.

Therefore, it is an object of the present invention to provide an improved complementary volumeaddef for controlling several slave pistons.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose, by way of example, the principle of the invention and thebest mode which has been contemplated of applying that principle.

In the single figure of the drawings, there is shown schematically the hydraulic system showing the present invention.

Referring to the drawing, there has been shown three slave cylinders 10, 11 and 12, respectively. Each slave cylinder is provided with a piston 14, 15 and 16, respectively, each mounted on a shaft 18, 19 and 20, respectively. The opposite ends of each slave cylinder are provided with hydraulic lines 21 leading to a pair of slave selector valves 2.2L and 22R, so designated to represent the selector valve connected to the left hand or right hand lines 21 respectively. Valves 22L and 22?. are arranged on a common shaft 24 so as to be driven together to conmeet with the opposite ends of a selected one of the slave cylinders, for example cylinder 10. Positioning of shaft 24 to any one of the three positions required to connect valves 22 with cylinders 10, 11 or 12 is effected by a suitable positioning device 25 such as disclosed in expired US. patent, Serial No. 2,197,867 (F. Klement). Inasmuch as valves 22 are also fully described in the expired patent referred to, further description here is not considered necessary other than to say that the central rotatable portion 26 of valves 22 is provided with a hollow central lead-in portion 2 7 hydraulically coupled to fluid leads 2.81. and 28R respectively.

The left end of both lead 28L and 28R terminates in a directional control valve 34) in the nature of a fluid cock having two =arcuate channels 32 formed in its rotatable interior portion 31. Portion 31 is arranged to be freely turned through degrees counter-clockwise from the position shown in the drawing by the shaft 33 of a directional control solenoid 34. Solenoid 34 is operable to establish two fluid paths, i.e., to either connect channels 32 as shown to leads 28 or to reverse the connections. A pair of manifolds 36 and 37 respectively are connected to valve 30 for passing fluid under pressure thereto from the complementary volume adder now to be described.

The complementary volume adder shown in the drawing includes three actuator cylinders 41, 42 and 44, the cylinders being so designated since cylinder 41 is arranged to displace one unit volume of fluid, cylinder 42 two unit volumes of fluid and cylinder 44 four unit volumes of fluid, so that any combination of fluid Volumes from 1 through 7 may be displaced by utilizing various combinations of thethree actuator cylinders. Within each actuator cylinder is a two headed piston designated 5 1, S2 and 54, respectively, the central connecting shaft portion of each piston being loosely pinned to a lever or bail 55. LeverS-S is pivoted at its left end to a frame member 56 so that any suitable drive means represented schematically by the member 57 can drive all the actuator pistons simultaneously in concert in two directions. The phrase in concert here is used in the sense that all pistons start and stop together thereby providing excellent controlled dynamics of motion in the system. Therefore, the term bail as it is used here refers to a mechanical means for simultaneously driving all actuator pistons in concert. As shown in the drawing, each actuator cylinder is provided with a pair of longitudinal slots 58 through which lever 55 extends. It is to be appreciated that actuator cylinders arranged in pairs, each having a separate piston, the pistons of each pair being commonly connected, would constitute an obvious equivalent to the single cylinder with its two-headed piston arrangement as shown. Lil e wise the two-headed piston shown could be replaced with a single piston without the connecting shaft shown. In this case lever "55 could pass directly through lateral holes in the pistons.

As thus arranged, the actuator pistons have effectively divided each actuator cylinder into a pair of complementary fluid chambers one of which will decrease in volume Whi e the other increases in volume under cyclic motion applied to lever 55. Ports 59 in the ends ofeach actuator cylinder are connected by hydraulic leads 60 to an actuator control valve 61 associated with each actuator cylinder.

Valve 61 includes a valve housing 62, valve stem. 63 having two spools thereon connected to a solenoid 64 and spring-loaded by a spring 65 in an upward direction. Fixed to stem 63 is a collar 66 which prevents the spools from going any farther upward than is shown in the drawing. Actuation of solenoid 64 will pull stem 63 downwardly to the dotted line position shown in the valve 61 associated with actuator cylinder 41. In the full line position shown in the drawing, each valve 61 connects the upper chamber of its actuator cylinder 41, 42 or 44 directly to the lower chamber whereas actuation of a solenoid 64, (for example that of actuator cylinder 41) will condition valve 61 to connect the upper chamber of cylinder 41 to manifold 37 and the lower chamber to manifold 36. Since manifolds 36 and 37 are hydraulically coupled via direction control valve 30 and cylinder valves 22 to slave cylinder 10, the piston 14 in cylinder will be displaced according to the volume of fluid displaced from actuator cylinder 41 under movement of lever 55. Thus, it can be seen that by energizing a com.- bination of solenoids 64 various units of fluid volume (from 1 to 7) can be directed under pressure to either manifold 36 or 37 for distribution to a selected one of a number of slave cylinders and then return to the opposite side of the actuators.

For purposes of completing the overall system, there is shown in the upper left hand corner of the drawing, a schematic arrangement for indicating the position of any of the slave pistons and exercising control of valve 30 so that any selected slave piston can be driven to a new address. For this purpose, there has been provided on the left end of shafts 18, 19 and 20, a rack 70 coacting with teeth (not shown) in a suitable analog-toaligital converting device 71, such, for example, as shown in US. 2,747,797. Therefore, device 71 will not be described further other than to say that there is provided at each of eight radial locations on a disk a binary combination of holes representing decimal digits from 0. to,7. Behind the disk of device 71 there is provided a photoresponsive unit 72 and in front of the disk (and not shown) is a light source for passing light through the various combinations of holes so that the rotational position of the disk may be sensed by unit 72. Signals from unit 72 therefore represent the various incremental displacements of piston 14 and are sent by lead 73 to a suitable forward-reverse control circuit 74 where the sig- I nals from lead 73 are compared with electrical address signals incoming on lead 75. Although any circuit suitable for the purpose might be used, one such circuit for performing the requisite comparison to determine the direction of the next move for piston 14 (in the example) is to be found in co-pending application, Serial No. 793,370, wherein a high-low-equal compare circuit is fully described. Thus, the actual position of slave piston 14 as sensed by signals on lead 73, may be compared by circuit 74 with address signals on lead 75 to determine whether piston 14 should be moved to the right or left within its cylinder. Additional suitable circuitry can be provided for determining the degree of each subsequent move. After the direction of thenext move has been determined, an output signal on lead 77 is sent to solenoid 34 to properly condition valve 30. With the degree of the move determined, suitable signals are sent to solenoids 64 via leads73 so as to call for the proper volume of fluid necessary to displace slave piston 14 to its new location corresponding to the address received by circuit 74.

Finally it is to be understood that the proper conditioning of valves 22, 30 and 61 to achieve a desired move by a selected slave piston will be established during a set-up time provided prior to commencement of each movement of lever 55. For example, if lever 55 is driven by a cam, there may be a substantial dwell at the top and bottom of each stroke.

While the invention has been particularly shown and described with reference to a preferred embodiment there of, it will be understood by those skilled in the art that various changes in the form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. 'A hydraulic system comprising a plurality of slave cylinders, each said slave cylinder having a movable piston therein, a first and second manifold alternately conditioned respectively to pressure and exhaust, fluid distribution means selectively coupling said manifolds hydraulically to opposite ends respectively of any one of said slave cylinders to drive the piston thereof, a fluid actuator system for conditioning said manifolds as aforesaid, said system comprising a plurality of actuator cylinders, piston means within each actuator cylinder and arranged to provide pairs of expansible fluid chambers, both chambers of each pair having a port therein arranged for fluid communication therewith, a mechanical drive bail directly coupled to said piston means and constructed and arranged to be driven alternately to opposite extremes to exhaust fluid from one chamber in each pair while admitting a commensurate amount of fluid into the other chamber of the pair, means defining a first fluid path hydraulically coupling the ports of both chambers in each pair to said first and second manifolds respectively to condition one of said manifolds to pressure and the other to exhaust thereby operating a selected slave cylinder, means defining a second fluid path hydraulically coupling the ports of both chambers in each pair and by passing said manifolds, and valve means common to both said paths for each pair of chambers, said valve means being arranged to select one or the other path for its associated pair of chambers, whereby said slave piston is displaced in proportion to the aggregate volume of fluid moved via said first paths under action of said drive bail.

2. The invention according to claim 1 wherein said bail is a lever pivoted at one end.

3. In a hydraulic system wherein a slave piston is arranged to be driven within an associated cylinder, an actuator comprising a pair of complementary expansible fluid displacement chambers, compression and expansion means associated with each of said chambers and constructed and arranged to decrease the volume of one while commensurately increasing the volume of the other, motive means for cyclically driving said compression and expansion means, a mechanical link coupling said compression and expansion means and said motive means to transmit the energy from the latter to the former to displace fluid from one of said chambers while admitting fluid into the other, first fluid passage means hydraulically coupling said chambers via the slave cylinder, second fluid passage means hydraulically coupling said chambers while bypassing the slave cylinder, and valve means common to both said first and second fluid passage means and arranged to select one or the other of said fluid passage means thereby selectively applying the fluid discharge from said chambers to drive said slave piston.

4. In a hydraulic system wherein a slave piston is arranged to be driven within an associated cylinder, an actuator comprising a plurality of pairs of complementary expansible fluid displacement chambers, compression and expansion means associated with both chambers of each pair and constructed and arranged to decrease the volume of one while commensurately increasing the volume of the other, motive means for cyclically driving said compression and expansion means, a mechanical link coupling all said compression and expansion means and said motive means to transmit the energy from the latter to the former to displace fluid fromv one of said chambers in each pair while admitting fluid into the other chamber of said fluid passage means for each pair thereby selectively applying the fluid discharge from a combination of said chambers to drive said slave piston accordingly.

No references cited. 

